/*
Given the string representations of two integers, return the string representation of the sum of those integers.

For example:

sumStrings('1','2') // => '3'
A string representation of an integer will contain no characters besides the ten numerals "0" to "9".
*/

function sumStrings(a, b) {
    let res = "",
        c = 0;
    a = a.split("");
    b = b.split("");
    while (a.length || b.length || c) {
        c += ~~a.pop() + ~~b.pop();
        res = (c % 10) + res;
        c = c > 9;
    }
    return res.replace(/^0+/, "");
}
